Daniel,
Since electronics and amps are near double the cost in Croatia, and if labor, wood, storage and transportation are relatively cheap, building horn loaded subs is the way to go.
However, in small rooms, the advantage of horn subs will be less, and you don’t get the low frequency extension until you couple several.
If you were consistently doing more shows in the 2000 person range, 8 or more Lab subs would be a good investment. It will not split up that well though, so you may loose on the cheap and cheerful rentals.
If most of your market is in the 200 person range, you are probably better off with more small ported cabinets than a few big Lab subs. Storage and transportation can be a major issue, and you will probably get more money faster with small units, and then could afford to expand into the larger market.
Many PA companies find they make more money with a “speakers on sticks” than anything else, bigger is not always better. There are advantages to being a “one box” house, but I really think there is such a difference between a small time DJ wanting to rent a sub for a little dance at a bar and an outdoor rave for 2000 that you are better off addressing them separately.
For rentals, I would be inclined to find an inexpensive plate amp and put it into a ported 15” speaker box. Put stacking feet and female receptacles on each box so they won’t vibrate off each other when in a stack. Every box can be sent out alone, or multiples as large as needed, and if you have an amp or speaker failure, you only are out one unit.
Art Welter